Reforms aimed at banning unpaid internships have been blocked after Tory backbenchers and the government spoke against the proposals in the Commons.
The draft legislation sought to ensure people were paid the minimum wage for workplace internships.
The bill's sponsor, Tory MP Alec Shelbrooke, said he wanted to "level the playing field" for youngsters.
But the government said it could "undermine existing employment laws".
The proposed National Minimum Wage (Workplace Internships) Bill would require companies to pay interns at least the minimum wage for their work.
The MP for Elmet and Rothwell, Mr Shelbrooke, said not paying interns had become the "acceptable face of unpaid labour in modern Britain" and should be banned.
He warned that the use of unpaid interns by MPs, more than 20 of whom were advertising such roles, sent a message to UK business that "exploiting" young workers was acceptable.
But the debate on Friday was forced to end after four-and-a-half hours of speeches, with Tory MPs David Nuttall and Philip Davies each speaking for more than an hour.
Also expressing his concerns was Bob Stewart, Tory MP for Beckenham, who said: "If they [the employers] have to pay internships then that comes off the bottom line, it's a cost to the business, and undoubtedly there will be fewer internships."
Business minister Margot James said the bill was legally "unnecessary".
She said: "While it's extremely well-intentioned, I do have concerns that it could have unintended consequences that might even undermine existing employment laws and protections.
"Legally the bill is unnecessary because... interns are eligible for the National Minimum Wage if they meet the definition of 'worker'.
"It doesn't matter what the individual or employer calls the arrangement, or whether or not the individual agreed not to be paid, only the reality of the employment arrangement matters and if interns are workers they are entitled to be paid."
Shadow business minister Gill Furniss said Labour supported the bill.
She added: "This is a system rigged in favour of those who can afford it, or perhaps better said, whose parents can afford it."
The Labour MP said these unpaid internships were "monopolised by the children of the wealthy" while poorer people were "shut out".
Ben Lyons, co-director of the Intern Aware campaign, said: "The government flunked an opportunity to tackle the problem of long-term unpaid internships, which leads to good jobs going to those who can afford to work for free, rather than the brightest and most hard-working."
Mr Shelbrooke asked for the debate on his bill to resume on 24 February, although it is unlikely to secure further parliamentary time.